Close allies of President Trump, led by former chief strategist Steve Bannon and deputy campaign manager David Bossie, are plotting a campaign of primary challenges against establishment Republicans who have regularly obstructed Trump’s agenda.

Bannon has begun holding private meetings with Republican primary challengers, vowing to support their efforts to unseat establishment Republicans, as well as with conservative mega-donor Robert Mercer, who has vowed to pour millions of dollars into their campaigns.

Mercer, a wealthy hedge fund manager who was one of Trump’s top donors during the 2016 campaign, has expressed a desire to target establishment Republican lawmakers and has already donated $300,000 to an anti-Flake super PAC with indications he is interested in giving more to unseat the senator.

In addition, Bannon’s political adviser, Andrew Surabian, announced he was leaving the White House to take a job at the pro-Trump organization Great America Alliance.

“The Republican establishment is trying to nullify the 2016 election,” Bannon told CBS News’ Charlie Rose in an interview on 60 Minutes. “[Senate Majority Leader] Mitch McConnell, and to a degree, [House Speaker] Paul Ryan. They do not want Donald Trump’s populist, economic nationalist agenda to be implemented. It’s very obvious. It’s very obvious what they are trying to do.”

Bannon recently met with Danny Tarkanian, an attorney who is challenging Nevada Senator Dean Heller, and pledged his complete support, according to one person familiar with the conversation. Heller notably refused to endorse Trump during the 2016 presidential campaign.

“I got in the race with the hope that there would be enthusiasm for my candidacy, and it’s far exceeded my hope,” Tarkanian said. “There’s a lot of frustration with Dean Heller.”

At the top of Bannon’s target list is Arizona Senator Jeff Flake, who recently published a book bashing President Trump and the populist agenda that brought him into office. David Bossie, Trump’s 2016 deputy campaign manager and the president of the conservative organization Citizens United, has launched an effort to recruit several primary challengers against Flake, including former Representative Matt Salmon, who has thus far expressed reluctance to enter the race.

Kelli Ward, a former state senator who unsuccessfully challenged John McCain in 2016, has already declared her candidacy against Flake.

In addition to Flake and Heller, Bannon has privately suggested the possibility of targeting Tennessee Senator Bob Corker and Mississippi Senator Roger Wicker.

Corker, the chairman of the Senate Foreign Relations Committee, was once considered for the position of Secretary of State, but angered many of Trump’s supporters after he made comments doubting the president’s competence. Breitbart, upon Bannon’s return, published a piece praising State Senator Mark Green, a potential primary challenger against Corker, as well as State Senator Chris McDaniel, who may challenge Wicker in Mississippi.

The first test of the anti-establishment campaign will come in Alabama, where former State Supreme Court Chief Justice Roy Moore is seeking to unseat Senator Luther Strange, who was appointed to fill the remainder of Jeff Sessions’ term when he was appointed Attorney General.

Bannon has pledged support for Moore, with both Bannon and Bossie meeting separately with Moore in Washington last week, while Senate Majority Leader Mitch McConnell and the Republican establishment has supported Strange. President Trump endorsed Strange before the first round of voting in August, but has done little to promote his candidacy.

Polls show Moore with a sizable lead over Strange.

“I don’t think anyone should be surprised at primary challenges in GOP Senate races, especially against those senators that have appeared to be less than helpful to the Trump agenda. And I think those primary challengers will be well funded,” said Ned Ryun, a conservative strategist who has written for Breitbart. “It’s a natural reaction by the base to what they’ve perceived as a perhaps intentional inability to pass any Trump agenda items.”

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